Apparatus for drying fabrics



July 9, 1946. G. D. ,BLUNK ET AL 2,403,530

APPARATUS FOR DRYING FABRICS Filed Nov. 8, 1943 g y \IT'JQ El y h I Q I l7 {ii :3 ll a y i 4| H a! 'I.: ii 19 :3 El ii p H I FIG. 1| 4 nz W a 5 D E I; so

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TIME CYCLE- MmurEs WITNESSES: F G 4 V INVENTORS O i u w? 477M I Gen: D BLUNK a o Hagan E. Enwpaos.

ATTo EY Patented July 9, 1946 Gene D. Blunk and Hilbert E. Edwards/ Manafleld, Ohio, assignors to Westinghouse Electric Corporation,

East Pittsburgh, tion of Pennsylvania Pm, a corpora- Applioation November 8; 1943, Serial No. 509,315 4 Claims. (01. 34-44:

Our invention relates to apparatus for drying fabrics and has for an object to provide improved apparatus of this kind.

A further object of the invention is to control operation of a drier for fabrics or the like in response to the humidity of a stream of heated air passed in contact with the fabrics.

A further object of the invention is to terminate operation of a drier for fabrics in response to a predetermined value of the humidity of air passed in contact with the fabrics during periods when the humidity is receding.

It is a still further object of our invention to terminate operation of a drier of the type set forth when the moisture content in the fabrics is optimum for the ironing of fabrics.

These and other objects are effected by our invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. 1 is a sectional view taken through a drier for fabrics or the like and constructed and arranged in accordance with our invention.

Figs. 2 and 3 are sectional views taken through a humidity responsive device shown in Fig. 1 and illustrating two positions of the device; and

Fig. 4 is a curve showing values of the humidity of air passed through the drier charted against time of operation.

Reference will now be had to the drawing wherein we have shown our invention. applied to a clothes drier of the domestic type which includes a casing l having a generally cylindrical drying chamber H formed therein. The casing has an inlet opening for air indicated at if formed in the rear thereof and a louvred air discharge opening it formed in the side thereof. A

duct It provides communication between the air inlet opening I! and the heating chamber II and a duct II serves to convey air and vaporized mois-. ture from the heating chamber l I to the air outlet opening li.

A generally cylindrical perforate basket I! is disposed within the heating chamber H and is movable about a substantially horizontal axis. Preferably, the basket i8 is formed of relatively heavy gauge wires welded together to provide a structure having large passages for air which is translated in contact with the fabrics within the basket It as described hereinafter. The basket i6 is provided with an opening (not shown) in an end thereof for the ingress and egress of the fabrics. The basket I6 is rotated at a relatively low speed of approximately 50 R. P. M. for tumbling the fabrics contained therein by means of an electric motor I! disposed adjacent the air inlet opening it. A belt ll defines the driving connection between the motor I! and the basket II The motor ll also serves to drive a fan I! which draws air from the ambient atmosphere through the opening i2 and through the duct I4, the heating chamber H and the duct II to the air outlet opening ll. During its passage'through the duct H the air is heated. preferably by means of an electric heater indicated at II. in order to increase its capacity for absorbing moisture from the fabrics in the besket it as is well understood. The duct ll, the heating chamber H and the duct ii are preferably covered with a heat insulating substance indicated at 22 in order to retard the flow of heat from the air contained therein.

In accordance with our invention, operation of the heater 2! is controlled by a humidity-responsive device indicated generally at I3 and disosed in the discharge duct II where it is subjected to the air subsequent to its contact with the wet fabrics. The humidity-responsive device 23 is constructed and arranged to terminate the heating or the air by the heater II in response to a predetermined value of the humidity of the vair and during periods when the humidity is being reduced. It will be apparent from Fig. 4 that the humidity of the air to which the device 23 is subjected increases during the early part'of the drying cycle as shown at A on the curve, then becomes substantially constant during the intermediate portion of the cycle as shown at B, and finally is reduced, as shown at C, during the latter part of the drying cycle. In one form of device which we have tested we found that the relative humidity in the discharge duct, after approximately two minutes of operation of the heater 2| and with a load of approximately 9 pounds of damp fabrics in the basket, was approximately 20 per cent. 'The relative humidity increased to approximately 58 per cent after 20 minutes of operation, as shown at A on the curve-and after 28 minutes of operation the relative humidity decreased, as shown at C on the curve, because of the dryness of the fabrics at this time. f It is an object of our invention to terminate the drying of the fabrics when the moisture content thereof is optimum for the ironing of the fabrics. We

have found that, if the drying operation is terminated when the relative humidity is receding and at a relative humidity value of approximately 50 per cent, the weight of the moisture in the which translates the air 3 fabrics is approximately 20 per cent of the dry weight of the fabrics beint treated. turecontentisoptimumfortheironingef fabrics. This relation between the moisture con- We have shown in Figs. 2 and 8 a humidostat which may be employed for controlling the operation of the drier. This instrument includes a housing 2' having a plurality of openings 22 formed in the walls thereof in order to provide for the free circulation of air within the housing,

2|. Arranged within the housing 2! is a switch. generally shown at 21, which is manually closed by a push button 2' and which is opened by a humidity-responsive element 2| of any well understood construction. The element 28 is formed of a suitable hygroscopic material and expands with an increase in moisture content of the air and which contracts with a decrease of the moisture content of the air.

The switch 21 includes first and second contacts Ii and 22, the former of which is actuated by the push button 22. This contact 2| is carried by a snap-acting overcenter spring 22, the ends of which are supported by studs 24 carried by a plate 25. The plate 2! is supported in the housing by an insulated bushing 22 and is electrically connected to a terminal 21 which is insulated from the housing 2!. Contact 22 is supported by a spring 28 which also defines a current-carrying member and which is electrically connected to a terminal 22 insulated from the housing 2!.

One end of the humidity-responsive element 22 is connected to a trigger Ii having an elongated slot 42 formed therein and within which a pin 42 is disposed. The latter is stationary and suitably supported by the housing 25. The trigger 4| is biased at all times clockwise about the pin 42 by a spring 44 secured to the housing structure 25. In order to provide for adjustment of the humidity at which the element 29 opens the switch 21, the opposite end of the humidity-responsive element 22 is secured to a pivoted lever 45, one end of which is inclined as shown at 40. The inclined end 48 rests upon a screw 41 which when rotated effects upward or downward movement of the lever 48 and, therefore, varies the position of the humidity-responsive element 2! and the trigger ll relative the contact 22 which they operate. According the switch 21 is opened at various values of the humidity of the air depending upon the adjustment of the screw The switch 21 controls energization of the heater 2i and, if desired, may also control the operation of the motor l1. Preferably, the switch 21 controls both the motor l1 and heater 2| as an extra control device for the motor is then forced overcenter to the switch open position by the element 2| and its trisger ll.

Operation In operating the drier, the wet' fabrics to be dried are deposited in the basket ll through its access opening (not shown). At this time, the positions of the various elements of the humidostat are as shown in Fig. 3. When the button 22 is depressed, the switch 21 is closed whereupon operation of the motor i1 and the heater 2| is initiated. The dry bulb temperature of the air subsequent to its passage through the heater 2i is materially increased and the relative humidity of the air substantially decreased. The passage of this relatively dry air in contact with the tumbling fabrics in the basket ll effects vaporization of the moisture in the fabrics, which vapor is discharged with the air through the outlet it. During the early stages of the cycle, the relative humidity of the air discharged from the fabrics progressively increases as shown by that portion of the curve indicated at A. Accordingly, the humidity-responsive element 29 lengthens, permitting the spring 44 to swing the trigger from the position shown in Fig. 3 to the position shown in Fig. 2. During this movement, the trigger is first swung about the pin 12 with the uppermost end of the trigger ll disposed below the contact 22. The arrangement is such that as the trigger is moved toward its vertical position. the bias of the spring ll will move the trigger upwardly upon the pin 22 to a position behind the contact 32 as shown in Fig. 2. This movement is afforded by the elongated slot 42. After the drier is in operation approximately 20 minutes, the evaporation of moisture from the fabrics becomes uniiorm and the relative humidity of the air in the discharge conduit 22 becomes substantially constant.

After a period 01 operation, for example, 28 minutes as shown on the chart, the relative humidity of the air in the duct it is progressively reduced as indicated at C on the chart because of the reduction in the amount of moisture in the fabrics at this time. Accordingly, the humidity-responsive element 29 contracts and moves the trigger ll counterclockwise about the pin 42.

When the relative humidity has been reduced to obviated. Fig. 2 shows the position of the various elements of the humidostat 22 during the operation of the motor and the heater 2i. Fig. 3 shows the position of the apparatus after the humidity-responsive element 22 has operated to trip the switch 21. It will be apparent that the switch 21 is maintained in its closed position the overcenter spring 22 until the latter is a predetermined value as determined by the adjustment of the humidostat, the trigger 4i forces the overcenter spring to the position shown in Fig. 3, whereupon the contacts 3! and 32 are disengaged. Subsequent to this operation, the trigger 4| is moved downwardly by the contracted element 28, this movement being afforded by the slot 42. Opening of the switch contacts 3| and 22 deenergizes the heater and the motor ii. The fabrics which have been dried to a predetermined degree may now be removed from the basket l6.

Preferably, the element 29 is adjusted to open the switch 21 when the amount of moisture remaining in the fabrics is optimum for the immediate ironing of the fabrics. As set forth heretoiore, the drying operation is terminated in response to the value of the relative humidity in the duct it which prevails when the proper amount of moisture remains in the fabrics. This humidity value can be determined readily from tests. In the form of drier which we have tested, we found that by terminating operation of the drier when the relative humidity was receding and at a value of approximately 50 per cent, the

amount of moisture in the fabrics was equivalent to substantially 20 per cent of the dry weight of ation of the drier is manually initiated and then automatically terminated in response to the humidity of the air discharged from the fabrics.

,Ihehumidity-responsive device is so constructed and arranged that it terminates operation of the drier only during periods'when'thehumidity is receding and at a predetermined value of the humidity. The value of the humidity at which operation is terminated is, preferably, the value prevailing at the time that the moisture content in the fabrics is optimum for the immediate ironing of the fabrics.

While we have shown our invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and we desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What we claim is:

1. In apparatus for drying damp fabrics or the like, the combination of a casing having an air inlet and an air outlet, a perforate basket for containing the fabrics, said basket being arranged within the casing and movable about an,

axis, means translating air from said inlet through the basket and thence through said outlet for vaporizing moisture contained in the fabrics, means for heating the translated air, means for actuating the basket about its axis, a switch for controlling operation of the heating means, manually-operated means for closing the switch, a humidity-responsive element subjected to the air discharged from the basket, and means connecting the humidity-responsive element and the switch for opening the latter, said connecting means being so constructed and arranged that the switch is opened by the element only during a reduction in the humidity of the discharged air and in response to a predetermined value of the humidity of the air.

2. The combination as claimed in claim 1 wherein said basket actuating means is under control of said switch;

3. In apparatus, for abstracting moisture from clamp fabrics or the like, the combination of a casing having an air inlet and an air outlet, means for tumbling the fabrics to be treated within said casing, means for translating air in contact with the fabrics and thence through said air outlet, means for heating said air, a switch manually closed for initiating operation of the heating means, and humidity-responsive means subjected to the air passing to said outlet for opening the switch, said humidity-responsive means including an element responsive to the humidity of the air and a trigger operated thereby and engageable with said switch for operation thereof during a reduction in the humidity of the air, said trigger being ineflective to operatethe switch during an increase in the humidity of the air.

4. The combination as claimed in claim 3 wherein operation of said tumbling means is controlled by said switch.

- GENE D: BLUNK.

nmma'r E. nnwnnns. 

